What is donnatal (phenobarbital atropine hyoscyamine and scopolamine)? I heard it's an optional therapy for ibs.

Moderate. The active ingredients in donnatal (phenobarbital atropine hyoscyamine and scopolamine) have been shown to be more effective than placebo in treating moderately severe symptoms of irritable bowel syndrome.
IBS medication. Donnatal (phenobarbital atropine hyoscyamine and scopolamine) is an elixir consisting of hyoscyamine, atropine, scopolamine, and phenobarbital, which is used in the treatment of irritable bowel syndrome (ibs). It is categorized as an anti-cholinergic / anti-spasmodic medication. It is commonly used as an adjunct to dietary modification for first line treatment of ibs. It is available in liquid or tablet form and taken up to 4 times per day.